石墨烯量子点在生物医学中的研究进展

石墨烯量子点是石墨烯超家族的衍生物,与高维度石墨烯相比,具有良好的生物相容性,较低的细胞毒性及较好的化学修饰性。自发现以来,石墨烯量子点的应用领域被逐渐地拓宽。其中石墨烯量子点的生物应用主要包括生物成像、生物传感器、药物运输、基因载体、抗菌抗病毒及肿瘤的光动力治疗研究等。主要介绍了近几年有关石墨烯量子点生物相容性及其在生物医学研究的进展,并对其发展前景进行了展望。     

输尿管支架表面化学接枝镀铜涂层及其性能

采用聚多巴胺接枝化学镀铜方法在316L不锈钢表面制备载铜聚多巴胺涂层,使用扫描电镜、原子力显微镜、X射线光电子能谱、电感耦合等离子体质谱仪等手段表征其表面形貌、成分和铜离子释放量并将其与细菌和细胞共培养,研究了涂层的抗感染、抗结石性能和生物相容性。结果表明,载铜涂层的厚度为27 nm,分布均匀,其中的铜以Cu、CuO和Cu₂O的形式存在。将涂层在人工尿液中浸泡14 d,铜离子每天的释放量接近。将涂层分别与大肠杆菌和金黄色葡萄球菌培养24 h后,抗菌率为96.2%和95.9%。在金黄色葡萄球菌悬液中浸泡30 d后在涂层表面沉积的钙离子和镁离子含量分别为48.7 mg/L和235.3 mg/L,明显低于对照组。细胞增殖实验的结果表明,这种涂层无细胞毒性。     

Novel biocompatible waterborne polyurethane using L‐lysine as an extender

Polyurethane (PU) prepolymers based on isophorone diisocyanates, dimethylolpropionic acid, and polycaprolactone were prepared and chain‐ extended in water using L ‐lysine (PU–L), ethylenediamine (PU–E), and their mixture (PU– L–E) as extenders, respectively. The produced emulsion exhibited satisfactory freeze/thaw stability. Films cast from emulsions exhibited excellent mechanical properties and good antiblood coagulation character. Although the water‐swelling ratio for 24 h for PU–L was higher than those of PU–L–E and PU–E, it possessed the smallest hydrolysis rate among the three samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2474–2480, 2002     

Surface modification of poly‐L‐lactide by photografting of hydrophilic polymers towards improving its hydrophilicity

Poly‐L ‐lactide (PLLA) has been used to prepare scaffolds to guide tissue regeneration in tissue engineering research. However, one of the limitations to the use of PLLA as an ideal biomaterial is its high hydrophobicity. To improve the hydrophilicity of PLLA, hydrophilic polymers were grafted onto PLLA membrane surfaces through the combination of photooxidization in hydrogen peroxide and subsequent ultraviolet (UV)‐induced grafting copolymerization in the monomer solution. Three kinds of modified PLLA membranes (i.e., PLLA‐g‐polyhydroxyethyl methacrylate, PLLA‐g‐polyacrylamide, and PLLA‐g‐polymethacrylic acid) were obtained, resulting in the more wettable PLLA membranes. The occurrence of the grafting polymerization was confirmed by attenuated total reflectance infrared spectroscopy (ATR‐IR) and X‐ray photoelectron spectroscopy (XPS) analysis. Surface morphology of the modified PLLA membranes was studied by scan electronic microscopy (SEM). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2163–2171, 2002     

Surface modification of silicone rubber by ion beam assisted deposition (IBAD) for improved biocompatibility

We studied the preparation of antimicrobial silicone rubbers of improved interfacial strength, which could be formed with the ion beam assisted deposition (IBAD) technique for coating metallic or inorganic materials (silver (Ag), Copper (Cu), and Hydroxyapatite(HAp)/TiO₂) on the silicone surface. Those coating materials provide high product safety as well as outstanding antimicrobial activity. The deposition methodology is composed of pre‐etching with oxygen gas, vaporizing the coating materials, and post‐treatment with Ar ion. With the evaporation of the coating materials, the Ar beam was focused on the substrate to assist deposition. It was found out that the ion assisting depositions in the IBAD process give a prominent enhancement in adhesion between silicone rubbers and coatings of Ag and Cu. The HAp/TiO₂ coating layer was easily dissolved in aqueous saline solution. All deposited layers display high antimicrobial activities against Staphlococcus aureus (ATCC 6538) and Escherichia coil (ATCC 25,922), showing 99.9% reduction of bacteria, respectively. In a cytotoxicity test, the Ag and HAp/TiO₂ coated silicone shows a decrease of cytotoxicity, while the Cu coating leads to a slight increase of cytotoxicity. The result on the surface modifications of silicone rubber will be employed in further study for applications of medical or rehabilitation devices. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1095–1101, 2005     

几种聚乳酸／生物活性陶瓷复合材料细胞相容性的比较

采用溶解共混法制备含30%硅灰石的聚乳酸/硅灰石新型生物医用复合物膜.将大鼠成骨细胞ROS 17/28系种植在复合物表面使其存活,考察生长情况和复合物的生物活性,并与目前研究应用较多的聚乳酸/羟基磷灰石、聚乳酸/磷酸三钙及聚乳酸/珍珠层粉复合物进行比较.荧光染色实验及MTT测试表明,4种复合物膜表面细胞均可以正常的生长和增殖,且呈现出聚乳酸/珍珠层粉>聚乳酸/硅灰石>聚乳酸/羟基磷灰石>聚乳酸/磷酸三钙的结果,说明聚乳酸/硅灰石复合物材料具有较好的细胞相容性,适于应用在骨修复及骨组织工程领域.     

Achieving Biocompatible SABRE: An in vitro Cytotoxicity Study

Production of a biocompatible hyperpolarized bolus for signal amplification by reversible exchange (SABRE) could open the door to simple clinical diagnosis via magnetic resonance imaging. Essential to successful progression to preclinical/clinical applications is the determination of the toxicology profile of the SABRE reaction mixture. Herein, we exemplify the cytotoxicity of the SABRE approach using in vitro cell assays. We conclude that the main cause of the observed toxicity is due to the SABRE catalyst. We therefore illustrate two catalyst removal methods: one involving deactivation and ion‐exchange chromatography, and the second using biphasic catalysis. These routes produce a bolus suitable for future in vivo study.     

Facile synthesis of extremely biocompatible double‐network hydrogels based on chitosan and poly(vinyl alcohol) with enhanced mechanical properties

An easy and ecofriendly method for designing double‐network (DN) hydrogels based on chitosan and poly(vinyl alcohol) (PVA) with high mechanical performance is described. When covalent bonds in the networks are used as crosslinking agents in the achievement of a higher mechanical strength, the irreversible deformation of these hydrogels after a large force is applied is still one of the most important obstacles. To overcome this problem, we used physical crosslinking for both networks. The mechanical strength, surface morphology, and cytotoxicity of the films were studied by tensile testing, scanning electron microscopy analysis, and an MTT assay. The synthesized chitosan–PVA DN hydrogels showed a large improvement in the tensile strength to 11.52 MPa with an elongation of 265.6%. The surface morphologies of the films demonstrated the effective interactions between the two networks and a suitable porosity. Also, because of the use of a natural polymer and honey as a plasticizer, the cell culture indicated that the synthesized DN hydrogels had good biocompatibility (with 327.49 ± 11.22% viability) and could be used as capable biomaterials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45752.     

An innovative α‐calcium sulfate hemihydrate bioceramic as a potential bone graft substitute

The microstructural, in vitro and in vivo properties of the microwave‐synthesized samples were investigated using the optical microscope, scanning electron microscope, X‐ray diffraction, differential scanning calorimeter, contact angle goniometer, cell cytotoxicity assay, and chick chorioallantoic membrane (CAM) model in the study. When the calcium sulfate dihydrate (CSD) precursor underwent microwave irradiation treatment at temperatures between 100°C and 160°C, the crystal morphologies and crystalline structures were transformed from (tablet‐like CSD (monoclinic)) → (tablet‐like CSD (monoclinic) + long column α‐calcium sulfate hemihydrate (α‐CSH, hexagonal)) → (long column CSD (monoclinic) + short column α‐CSH (hexagonal)) → (uniform short column α‐CSH (hexagonal)). The high‐purity α‐CSH with uniform short column crystals around 10 μm in length can be synthesized at 160°C for 10 minutes and exhibits a higher hydrophilic feature in blood. Moreover, the cell cytotoxicity assay indicated that the microwave‐synthesized samples possessed well biocompatibility. In vivo results also demonstrated that the microwave‐synthesized α‐CSH not only induces angiogenesis formation but also facilitates osteogenesis. Therefore, the microwave‐synthesized α‐CSH is a promising bone graft substitute that can be applied in dental and orthopedic fields.